Change of deformation mode caused by aging of Ti-14 mass%Mo alloy single crystals and embrittlement mechanism due to the ω-phase

Yoshito Takemoto, Moritaka Hida, Eiiti Sukedai, Akira Sakakibara

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18 Citations (Scopus)

Abstract

A change of deformation modes in lattice instable Ti-14 mass%Mo alloy single crystals upon aging treatments at 623 K was investigated in the tensile test up to rupture. The tensile direction of these specimens was [116]B. The main deformation modes of as-quenched specimen (AQ) were {332} 〈113〉 and {112} 〈111〉 mechanical twins. Their Schmid factors (SF) were 0.321 and 0.156 in {332} 〈113〉 twins and 0.447 in {112} 〈111〉 twins. A specimen aged for a short time of nearly 250 s (AG (S)) showed a kind of transitional state of deformation mode which involved {332} 〈113〉 twins, {112} 〈111〉 twins and {112} 〈111〉 slips. In this state AG(S) had been already poor in ductility. A specimen long aged for 1 × 105 s (AG(L)) showed a remarkable brittle fracture caused by the aged ω phase, but it was not the {001} cleavage fracture. The fracture surface had a chevron pattern induced by the operation of some {112} slip systems in the initial stage. Large grown aged ω variants caused the B matrix to remarkably increase the stress level for deformation and induced locally an Ω→B inverse transformation. Local softening which occurred with the inverse transformation led to an extreme stress concentration and then to crack. In this way AG(L) apparently showed notable embrittlement.

Original languageEnglish
Pages (from-to)1004-1012
Number of pages9
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume53
Issue number10
Publication statusPublished - Oct 1989

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embrittlement
Embrittlement
Aging of materials
Single crystals
single crystals
slip
stress concentration
Brittle fracture
tensile tests
ductility
Crystal lattices
softening
Ductility
Stress concentration
cleavage
cracks
Cracks
matrices

ASJC Scopus subject areas

  • Metals and Alloys

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Change of deformation mode caused by aging of Ti-14 mass%Mo alloy single crystals and embrittlement mechanism due to the ω-phase. / Takemoto, Yoshito; Hida, Moritaka; Sukedai, Eiiti; Sakakibara, Akira.

In: Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, Vol. 53, No. 10, 10.1989, p. 1004-1012.

Research output: Contribution to journalArticle

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AB - A change of deformation modes in lattice instable Ti-14 mass%Mo alloy single crystals upon aging treatments at 623 K was investigated in the tensile test up to rupture. The tensile direction of these specimens was [116]B. The main deformation modes of as-quenched specimen (AQ) were {332} 〈113〉 and {112} 〈111〉 mechanical twins. Their Schmid factors (SF) were 0.321 and 0.156 in {332} 〈113〉 twins and 0.447 in {112} 〈111〉 twins. A specimen aged for a short time of nearly 250 s (AG (S)) showed a kind of transitional state of deformation mode which involved {332} 〈113〉 twins, {112} 〈111〉 twins and {112} 〈111〉 slips. In this state AG(S) had been already poor in ductility. A specimen long aged for 1 × 105 s (AG(L)) showed a remarkable brittle fracture caused by the aged ω phase, but it was not the {001} cleavage fracture. The fracture surface had a chevron pattern induced by the operation of some {112} slip systems in the initial stage. Large grown aged ω variants caused the B matrix to remarkably increase the stress level for deformation and induced locally an Ω→B inverse transformation. Local softening which occurred with the inverse transformation led to an extreme stress concentration and then to crack. In this way AG(L) apparently showed notable embrittlement.

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